Some new results concerning the dynamic behavior of annular turbulent seals

The dynamic characteristics of annular turbulent seals applied in high pressure turbopumps can be described by stiffness, damping, and inertia coefficients. An improved procedure is presented for determining these parameters by using measurements made with newly developed test equipment. The dynamic system seal, consisting of the fluid between the cylindrical surfaces of the rotating shaft and the housing, is excited by test forces (input), and the relative motion between the surfaces (output) is measured. Transformation of the input and output time signals into the frequency domain leads to frequency response functions. An analytical model, depending on the seal parameters, is fitted to the measured data in order to identify the dynamic coefficients. Some new results are reported that show the dependencies of these coefficients with respect to the axial and radial Reynolds numbers and the geometrical data of the seal

Reconsidering the evidence: Are Eurozone business cycles converging

This paper, using 40 years of monthly industrial production data, examines the relationship between the business cycles of the 12 Eurozone countries. Since estimates of the business cycle have been found to be sensitive to how the cycle is measured, a range of alternative measures are considered. We focus on both parametric and nonparametric univariate measures of the ‘classical’ and ‘growth’ cycles. We then investigate whether Eurozone business cycles have converged. This is based on an analysis of the distribution of bivariate correlation coefficients between the 12 countries’ business cycles. This extends previous work that has tested for convergence, in a similar manner by focusing on correlation, but has not considered the entire distribution, instead focusing on the mean correlation coefficient or particular bivariate correlation coefficients. Although empirical inference about individual Eurozone business cycles is found to be sensitive to the measure of the business cycle considered, our measure of convergence between the Eurozone business cycles exhibits common features across the alternative measures of the business cycle. Interestingly, we find that there have been periods of convergence, identified by the distribution tending to unity, and periods of divergence. Although further data are required to corroborate the story, there is evidence to suggest that the Euro-zone has entered a period of convergence after the clear period of divergence in the early 1990s in the aftermath of German unification and at the time of the currency crises in Europe. This is encouraging for the successful operation of a common monetary policy in the Eurozone. --

When does vapor pressure deficit drive or reduce evapotranspiration?

Increasing vapor pressure deficit (VPD) increases atmospheric demand for water. While increased evapotranspiration (ET) in response to increased atmospheric demand seems intuitive, plants are capable of reducing ET in response to increased VPD by closing their stomata. We examine which effect dominates the response to increasing VPD: atmospheric demand and increases in ET, or plant response (stomata closure) and decreases in ET. We use Penman-Monteith, combined with semi-empirical optimal stomatal regulation theory and underlying water use efficiency, to develop a theoretical framework for assessing ET response to VPD. The theory suggests that depending on the environment and plant characteristics, ET response to increasing VPD can vary from strongly decreasing to increasing, highlighting the diversity of plant water regulation strategies. The ET response varies due to: 1) climate, with tropical and temperate climates more likely to exhibit a positive ET response to increasing VPD than boreal and arctic climates; 2) photosynthesis strategy, with C3 plants more likely to exhibit a positive ET response than C4 plants; and 3) plant type, with crops more likely to exhibit a positive ET response, and shrubs and gymniosperm trees more likely to exhibit a negative ET response. These results, derived from previous literature connecting plant parameters to plant and climate characteristics, highlight the utility of our simplified framework for understanding complex land atmosphere systems in terms of idealized scenarios in which ET responds to VPD only. This response is otherwise challenging to assess in an environment where many processes co-evolve together

Strong Consistency of the Least-Squares Estimator in Simple Regression Models with Stochastic Regressors

Strong consistency of least squares estimators of the slope parameter in simple linear regression models is established for predetermined stochastic regressors. The main result covers a class of models which falls outside the applicability of what is presently available in the literature. An application to the identification of economic models with adaptive learning is discussed

Consistent estimation of structural parameters in regression models with adaptive learning

In this paper we consider regression models with forecast feedback. Agents' expectations are formed via the recursive estimation of the parameters in an auxiliary model. The learning scheme employed by the agents belongs to the class of stochastic approximation algorithms whose gain sequence is decreasing to zero. Our focus is on the estimation of the parameters in the resulting actual law of motion. For a special case we show that the ordinary least squares estimator is consistent

Social relationships and identities in Manuel Rojas’ early work

Indexación: Web of Science; ScieloEste trabajo explora las novedades que Manuel Rojas introduce en su primera narrativa, específicamente con respecto a la identidad y al vínculo social del sujeto marginal. A través del análisis de sus cuentos, en especial "El delincuente" y "El vaso de leche", se busca develar el sustrato ideológico de esta nueva forma de representación, que coincide con el advenimiento del protagonismo político y social de los grupos populares en la historia de Chile y que constituye el fundamento de su novelística posterior. Palabras clave: Manuel Rojas, narrativa chilena del siglo XX, identidades, sujeto marginal.This article explores the new perspectives provided by Manuel Rojas’ early work regarding identity and social relationships of marginal subjects. Reading Rojas’ short stories, specially "El delincuente" and "El vaso de leche", we try to determine the ideological substrate of these new representations, which arrive simultaneously with the main role taken by popular groups in Chilean history and constitute the foundation of Rojas’ later novels. Key words: Manuel Rojas, XX century Chilean narrative, identities, marginal subject

Differential toxicity of gold-doxorubicin in cancer cells vs. cardiomyocytes as measured by real-time growth assays and fluorescence lifetime imaging microscopy (FLIM)

The kinetics of toxicity of doxorubicin (Dox) and gold nanoparticle-conjugated doxorubicin (Au-Dox) were investigated in cultured B16 melanoma cells and cardiomyocytes using real-time cell-growth imaging. Both bolus exposure and continuous exposure were used. Modeling of the growth curve dynamics suggested patterns of uptake and/or expulsion of the drug that were different for the different cell lines and exposures. Dox alone in B16 cells fit to a model of slow drug buildup, whereas Au-Dox fit to a pattern of initial high drug efficacy followed by a decrease. In cardiomyocytes, the best fit was to a model of increasing drug concentration which then began to decrease, consistent with breakdown of the doxorubicin in solution. Cardiomyocytes were more sensitive than B16 cells to Dox alone (IC_(50) 123 ± 2 nM vs. 270 ± 2 nM with continuous exposure), but were dramatically less sensitive to Au-Dox (IC_(50) 1 ± 0.1 μM vs. 58 ± 5 nM with continuous exposure). Bolus exposure for 40 min led to significant cell death in B16 cells but not in cardiomyocytes. Fluorescence lifetime imaging (FLIM) showed different patterns of uptake of Au-Dox in the two cell types that explained the differential toxicity. While Au-Dox concentrated in the nuclei of B16 cells, it remained endosomal in cardiomyocytes. These results suggest that stable conjugates of nanoparticles to doxorubicin may be useful for treating resistant cancers while sparing healthy tissue

Socio-economic vulnerability of coastal communities in southern Thailand: The development of adaptation strategies

The tsunami of December 2004 impacted large areas of Thailand's coastline and caused severe human and economic losses. The recovery period revealed differences in the vulnerabilities of communities affected. An understanding of the causal factors of vulnerability is crucial for minimising the negative effects of future threats and developing adaptive capacities. This paper analyses the vulnerabilities and the development of adaptation strategies in the booming tourist area of Khao Lak and in the predominantly fishing and agricultural area of Ban Nam Khem through a comprehensive vulnerability framework. The results show that social networks played a crucial role in coping with the disaster. Social cohesion is important for strengthening the community and developing successful adaptation strategies. The development of tourism and the turning away from traditional activities have a significant positive influence on the income situation, but create a dependency on a single business sector. It could be shown that households generating their income in the tourism sector were vulnerable unless they had diversified their income previously. Income diversification decreased the vulnerability in the study areas. Adaptation strategies and processes developed in the aftermath clearly address these issues